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1991-11-19
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1.0 INTRODUCTION
The NetBIOS packet driver found in the Clarkson collection has been
heavily modified to correct deficiencies and to change it from a
type 6 to a type 1 packet driver. This document describes the new
NetBIOS packet driver and explains how to use the packet driver to
support concurrent operation of TCP/IP application software
packages and NetBIOS based applications such as Lantastic.
2.0 BACKGROUND
Lantastic is an inexpensive Networking Operating System (NOS) that
provides most of the features required by smaller organizations.
Unfortunately, Lantastic does not support packet drivers. As a
result, it is difficult to use popular "freeware" TCP/IP packages
(such as NCSA Telnet, POPmail and TRUMPET) concurrently with
Lantastic.
Lantastic uses NetBIOS to provide session layer (and below)
services. Hence, one approach to providing concurrent Lantastic -
TCP/IP operation is to purchase an RFC 1001/1002 compliant NetBIOS
implementation. As most people purchase Lantastic because of its
low cost and because they wish to use "freeware" TCP/IP packages,
it is unlikely that they will want to spend yet more money on
another NetBIOS implementation. In addition, this approach will
only provide TCP/IP support to those application which can interact
with the TCP/IP stack on which the RFC 1001/1002 compliant NetBIOS
is based.
Another approach is to use the Lantastic NetBIOS implementation as
the "data link" on which to transmit IP packets. As there is a
NetBIOS packet driver in the Clarkson collection, this approach
appears to be viable. Unfortunately, the NetBIOS packet driver
presently found in the Clarkson collection has a number of
deficiencies whichb render it virtually unusable, especailly in
configurations which have Internet gateways.
While the Clarkson NetBIOS packet driver has its flaws, it does
contain the basic code needed to provide the required services.
Hence, it was decided to update the packet driver. Work started on
upgrading the packet driver nearly two years ago. A working
version was in operation within two weeks, with updates being made
to improve operation every few months.
The original NetBIOS packet driver was a class 6 packet driver. Up
until about a month ago, the updated NetBIOS packet driver was also
a class 6 packet driver. The inability of a number of popular
TCP/IP application packages to deal with class 6 packet drivers
resulted in the development of EtherSLIP, a SLIP mode packet driver
which provides a class 1 interface to the application software
packages. Ideas and code from EtherSLIP development were used to
modify the NetBIOS packet driver such that it also is now a class
1 packet driver.
The NetBIOS packet driver has been tested and found to operate
correctly with a number of TCP/IP packages, including NCSA Telnet,
POPmail, PC_gopher, TRUMPET, CUTCP, ka9q, and PC/TCP from FTP
Software.
3.0 THEORY OF OPERATION
This section provides a brief description of how the NetBIOS packet
driver operates. It is assumed that the reader is familiar with
the basic operation of packet drivers, NetBIOS and the Internet
Protocol. An understanding of how the NetBIOS packet driver is not
reqquired to make use of the packet driver. Hence, this section
can be skipped if the reader does not wish to understand the
internals of the NetBIOS packet driver.
The NetBIOS packet driver accepts complete Ethernet frames from the
application software, strips the Ethernet header, and uses the
NetBIOS datagram service to send the IP packet contained in the
data portion of the Ethernet frame.
On the receive side, the NetBIOS packet driver extracts IP packets
from incoming NetBIOS datagrams. An Ethernet header is prepended
to the IP packet and the resulting Ethernet frame is passed to the
application software package. The source address in the Ethernet
header is formed from the source NetBIOS address while the
destination address is set based on the local IP address.
Since the NetBIOS packet driver is a class 1 packet driver,
application software packages will likely use the Address
Resolution Protocol (ARP) to translate the IP address to an
appropriate data link address. Though it might be possible to
support ARP using NetBIOS, the present NetBIOS packet driver traps
all ARP requests and formulates its own ARP reply. Address
translation is simple; the target data link address is set to the
target IP address.
NetBIOS datagrams are directed to specific destinations as
identified by a NetBIOS name. When sending an IP packet, the
NetBIOS name for the destination machine is constructed by
appending the address found in the destination address field of the
Ethernet header to the string "TCPIP".
4.0 INSTALLATION
Concurrent operation of TCP/IP application software and NetBIOS
based software such as Lantastic requires installation of the
NetBIOS packet driver on each PC and the provision of a NetBIOS
gateway. This section examines both these installation issues in
some detail.
4.1 NetBIOS Packet Driver Installation
The NetBIOS Packet driver is invoked on each computer using the
following command line:
nb <int_no> [-g] <ip_address>
where:
<int_no> is the interrupt vector on which the
packet driver receives commands.
<ip_address> is the IP address of the local host.
-g gateway flag; only needed on the machine
which is to be the NetBIOS gateway.
4.2 NetBIOS Gateway
The NetBIOS packet driver encapsulates IP packets inside NetBIOS
datagrams. In order for applications packages using the NetBIOS
packet driver to exchange IP packets with machines which do not
support NetBIOS, some form of gateway is required. Though most (if
not all) commercial routers do not support NetBIOS encapsulation,
it is possible to implement such a gateway using PC based router
software which supports class 1 packet drivers. Two such packages
are PCroute and ka9q.
The PC based NetBIOS gateway must use two Ethernet boards, one to
handle raw Ethernet frames and one to handle NetBIOS packets.
NetBIOS software is required to provide the NetBIOS interface;
Artisoft's NetBIOS implementation is needed if Lantastic is to be
supported concurrently. As well, the NetBIOS packet driver must be
loaded with the gateway flag specified on the command line.
Rather than try to explain in general terms how to configure a
NetBIOS gateway, the configuration file for a ka9q based NetBIOS
gateway will be examined, line by line. In particular, note that
PROXY ARPS and static routes for each of the machines running the
NetBIOS packet driver. This configuration has been tested and is
known to work.
#
# This entry tells the ka9q software the name of your machine.
#
hostname hawkeye.nstn.ns.ca
#
# This entry contains your IP address. Brackets are required.
#
ip address [192.70.224.3]
#
# The attach command tells the ka9q software about the interfaces
# in your computer that you will be using for TCP/IP.
#
# Specify packet driver for "raw" Ethernet packet driver.
#
attach packet 0x61 ec0 25 1500
#
# Specify IP address for the interface using the "ifconfig"
# command.
#
ifconfig ec0 ipaddr [192.70.224.3]
#
# Specify packet driver for NetBIOS packet driver.
#
attach packet 0x60 nb0 25 1500
#
# Set up the ka9q software to PROXY ARP for each of the
# PCs on which the NetBIOS packet driver is running.
#
arp publish [192.70.224.2] ether 00:00:c0:48:92:19
arp publish [192.70.224.5] ether 00:00:c0:48:92:19
arp publish [192.70.224.6] ether 00:00:c0:48:92:19
arp publish [192.70.224.7] ether 00:00:c0:48:92:19
arp publish [192.70.224.8] ether 00:00:c0:48:92:19
arp publish [192.70.224.9] ether 00:00:c0:48:92:19
arp publish [192.70.224.10] ether 00:00:c0:48:92:19
arp publish [192.70.224.11] ether 00:00:c0:48:92:19
arp publish [192.70.224.12] ether 00:00:c0:48:92:19
arp publish [192.70.224.13] ether 00:00:c0:48:92:19
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